Internal combustion engine electronic ignition system having an engine speed sensitive variable ignition spark retard feature

Abstract

During the presence of a selected internal combustion engine operating parameter such as a coolant temperature range, the alternating current timing signals induced in the output coil of an electrical generator assembly having at least a rotor member rotated in timed relationship with the engine are overridden by the output signal of a circuit combination that produces the output signal during the positive going portion of each of the timing signals and maintains the output signal for a period of time that varies inversely in duration as the potential level with respect to ground of an engine speed variable potential signal varies directly with engine speed to provide an engine speed ignition spark retard that diminishes substantially linearly in value from maximum to minimum between selected first lower and second higher engine speeds.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 
     
       1. An internal combustion engine electronic ignition system having an engine speed sensitive variable ignition spark retard feature that is operational only during the presence of at least one selected engine operating parameter to provide an ignition spark retard that diminishes substantially linearly in value from maximum to minimum between selected first lower and second higher engine speeds and being of the type that effects an ignition spark event in response to a selected electrical polarity transition of each of a series of alternating current timing signals that are induced in the pickup coil of an electrical generator assembly having a rotor member rotated in timed relationship with the engine, comprising: means responsive to each of said series of alternating current timing signals for producing during the half cycle thereof immediately preceding said selected electrical polarity transition an ignition spark retard signal that is effective to override the effect of said alternating current timing signals in a manner to delay the occurrence of an ignition spark event;   means responsive to each said selected electrical polarity transition of said alternating current timing signals for initiating the production of a variable ignition spark retard value determining electrical signal that varies substantially linearly in potential level magnitude with time and wherein a given variation in potential level magnitude substantially represents an ignition spark event retard value in engine crankshaft degrees;   means for producing an engine speed variable reference potential signal that is a function of the amplitude of said timing signals and that varies directly with engine speed over an engine speed range between said selected first lower and second higher speeds; and   means responsive to said variable ignition spark retard value determining signals and said engine speed variable reference potential signal for terminating said ignition spark retard signal when said variable ignition spark retard value determining signal varies to a potential level magnitude substantially equal to that of said engine speed variable reference potential signal to thereby effect an ignition spark event, the variation in magnitude of said engine speed variable reference potential signal and said ignition spark retard determining signal being such that the amount of ignition retard decreases substantially linearly with increasing engine speed between said first and second selected engine speeds.   
     
     
       2. An internal combustion engine electronic ignition system having an engine speed sensitive variable ignition spark retard feature that is operational only during the presence of at least one selected engine operating parameter to provide an ignition spark retard that diminishes substantially linearly in value from maximum to minimum between selected first lower and second higher engine speeds and being of the type that effects an ignition spark event in response to a selected electrical polarity transition of each of a series of alternating current timing signals that are induced in the pickup coil of an electrical generator assembly having a rotor member rotated in timed relationship with the engine, comprising: means responsive to each of said series of alternating current timing signals for producing during the half cycle thereof immediately preceding said selected electrical polarity transition an ignition spark retard signal that is effective to override the effect of said alternating current timing signals in a manner to delay the occurrence of an ignition spark event;   means responsive to each said selected electrical polarity transition of said alternating current timing signals for initiating the production of a variable ignition spark retard value determining electrical signal that varies substantially linearly in potential level magnitude with time and wherein a given variation in potential level magnitude substantially represents an ignition spark event retard value in engine crankshaft degrees;   means for producing an engine speed variable reference potential signal that is a function of the amplitude of said timing signals and that varies directly with engine speed over an engine speed range between said selected first lower and second higher speeds;   means responsive to said variable ignition spark retard value determining signal and said engine speed variable reference potential signal for terminating said ignition spark retard output signal when said variable ignition spark retard value determining signal varies to a potential level magnitude substantially equal to that of said engine speed variable reference potential signal to thereby effect an ignition spark event, the variation in magnitude of said engine speed variable reference potential signal and said ignition spark retard determining signal being such that the amount of ignition retard decreases substantially linearly with increasing engine speed between said first and second selected engine speeds; and   means responsive to the further variation of said variable ignition spark retard value determining signal in the same direction to another different potential level of a selected magnitude for effecting a substantially linear opposite direction variation of potential level thereof with time.   
     
     
       3. An internal combustion engine electronic ignition system having an engine speed sensitive variable ignition spark retard feature that is operational only during the presence of at least one selected engine operating parameter to provide an ignition spark retard that diminishes substantially linearly in value from maximum to minimum between selected first lower and second higher engine speeds and being of the type that effects an ignition spark event in response to a selected electrical polarity transition of each of a series of alternating current timing signals that are induced in the pickup coil of an electrical generator assembly having a rotor member rotated in timed relationship with the engine, comprising: means responsive to each of said series of alternating current timing signals for producing during the half cycle thereof immediately preceding said selected electrical polarity transition an ignition spark retard signal that is effective to override the effect of said alternating current timing signals in a manner to delay the occurrence of an ignition spark event;   means for producing a variable electrical signal of the type that is substantially linearly variable in potential level magnitude with time in each of two opposite directions;   means responsive to each said selected electrical polarity transition of said alternating current timing signals for effecting a variation of the potential level of said variable electrical signal in a selected first direction to produce a variable ignition spark retard value determining electrical signal that varies substantially linearly in potential level magnitude with time and wherein a given variation in potential level magnitude substantially represents an ignition spark event retard value in engine crankshaft degrees;   means for producing an engine speed variable reference potential signal that is a function of the amplitude of said timing signals and that varies directly with engine speed over an engine speed range between said selected first lower and second higher speeds;   means responsive to said variable ignition spark retard value determining signal and said engine speed variable reference potential signal for terminating said ignition spark retard output signal when said variable ignition spark retard value determining signal varies to a potential level magnitude substantially equal to that of said engine speed variable reference potential signal to thereby effect an ignition spark event, the variation in magnitude of said engine speed variable reference potential signal and said ignition spark retard determining signal being such that the amount of ignition retard decreases substantially linearly with increasing engine speed between said first and second selected engine speeds; and   means responsive to the further variation of said electrical signal in the same direction to another different potential level of a selected magnitude for effecting a substantially linear opposite direction variation of potential level thereof with time.   
     
     
       4. An internal combustion engine electronic ignition system having an engine speed sensitive variable ignition spark retard feature that is operational only during the presence of at least one selected engine operating parameter to provide an ignition spark retard that diminishes substantially linearly in value from maximum to minimum between selected first lower and second higher engine speeds and being of the type that effects an ignition spark event in response to a selected electrical polarity transition of each of a series of alternating current timing signals that are induced in the pickup coil of an electrical generator assembly having a rotor member rotated in timed relationship with the engine, comprising: means responsive to each of said series of alternating current timing signals for producing during the half cycle thereof immediately preceding said selected electrical polarity transition an ignition spark retard signal that is effective to override the effect of said alternating current timing signals in a manner to delay the occurrence of an ignition spark event;   a capacitor;   a current mirror source circuit arrangement capable of charging said capacitor upon and during the application of operating potential;   a current mirror sink circuit arrangement selectively activable to sink the current supplied by said current mirror source circuit arrangement and to discharge said capacitor;   means responsive to each said selected electrical polarity transition of said alternating current timing signals for activating said current mirror sink circuit arrangement to discharge said capacitor and thereby produce a variable ignition spark retard value determining electrical signal that varies substantially linearly in potential level magnitude with time and wherein a given variation in potential level magnitude substantially represents an ignition spark event retard value in engine crankshaft degrees;   means for producing an engine speed variable reference potential signal that is a function of the amplitude of said timing signals and that varies directly with engine speed over an engine speed range between said selected first lower and second higher speeds; and   means responsive to said variable ignition spark retard value determining signal and said engine speed variable reference potential signal for terminating said ignition spark retard output signal when said variable ignition spark retard value determining signal varies to a potential level magnitude substantially equal to that of said engine speed variable reference potential signal to thereby effect an ignition spark event, the variation in magnitude of said engine speed variable reference potential signal and said ignition spark retard determining signal being such that the amount of ignition retard decreases substantially linearly with increasing engine speed between said first and second selected engine speeds.   
     
     
       5. An internal combustion engine electronic ignition system having an engine speed sensitive variable ignition spark retard feature that is operational only during the presence of at least one selected engine operating paramter to provide an ignition spark retard that diminishes substantially linearly in value from maximum to minimum between selected first lower and second higher engine speeds and being of the type that effects an ignition spark event in response to a selected electrical polarity transition of each of a series of alternating current timing signals that are induced in the pickup coil of an electrical generator assembly having a rotor member rotated in timed relationship with the engine, comprising: means responsive to each of said series of alternating current timing signals for producing during the half cycle thereof immediately preceding said selected electrical polarity transition an ignition spark retard signal that is effective to override the effect of said alternating current timing signals in a manner to delay the occurrence of an ignition spark event;   a capacitor;   a current mirror source circuit arrangement capable of charging said capacitor upon and during the application of operating potential;   a current mirror sink circuit arrangement selectively activable to sink the current supplied by said current mirror source circuit arrangement and to discharge said capacitor;   means responsive to each said selected electrical polarity transition of said alternating current timing signals for activating said current mirror sink circuit arrangement to discharge said capacitor and thereby produce a variable ignition spark retard value determining electrical signal that varies substantially linearly in potential level magnitude with time and wherein a given variation in potential level magnitude substantially represents an ignition spark event retard value in engine crankshaft degrees;   means for producing an engine speed variable reference potential signal that is a function of the amplitude of said timing signals and that varies directly with engine speed over an engine speed range between said selected first lower and second higher speeds;   means responsive to said variable ignition spark retard value determining signal and said engine speed variable reference potential signal for terminating said ignition spark retard output signal when said variable ignition spark retard value determining signal varies to a potential level magnitude substantially equal to that of said engine speed variable reference potential signal to thereby effect an ignition spark event, the variation in magnitude of said engine speed variable reference potential signal and said ignition spark retard determining signal being such that the amount of ignition retard decreases substantially linearly with increasing engine speed between said first and second selected engine speeds; and   means responsive to the further variation of said variable ignition spark retard determining signal in the same direction to another different voltage level of a selected magnitude for deactivating said current mirror sink circuit arrangement whereby said current mirror source circuit arrangement charges said capacitor.